The invention relates to cyclones and, more particularly, to throw-away apexes and quick release means for exchanging worn apexes for new ones.
Cyclones and hydrocyclones are devices which are used in various industries to separate different size particles that are fed as a mixture into a cyclone inlet. In ore processing industries, cyclones are in circuit with grinding mills and are usually assembled in a circular "cluster" over a circular "tub" into which the coarser particles passing through the cyclone are discharged and fed back into the grinding mill. The outlet or overflow of the cyclone is where the fine particles that are internally separated pass out of the cyclone. As those skilled in the art know, cyclones include as their primary components an inlet, a cone section which tapers down from a large diameter to a small diameter, an internal vortex finder, and an outlet through which fine particles and liquid carrying them are discharged. As the coarse particles rotate and fall toward the apex, the density thereof increases and abrasion caused thereby increases. Since the primary function of the apex orifice of a cyclone is to discharge the coarse material at the highest possible density, and since the amount of water leaving the cyclone with the coarse material is critical, the proper apex diameter for a particular cyclone and set of operating conditions also is critical. If the apex orifice is too small, the cyclone will plug, and the entire cyclone feed, including the coarse particles, will pass out of the cyclone overflow outlet. On the other hand, if the apex orifice is too large, excessive amounts of water pass out of the lower end or underflow of the cyclone. Such excessive amounts of water passing through the cyclone underflow outlet pull excessive amounts of the fine particles that should otherwise "separate" into the vortex section and be discharged as overflow. The fine particles then unnecessarily pass back through the grinding mill, resulting in an inefficient milling operation. Other factors than apex diameter also strongly effect the performance of the cyclone, including the inlet feed density, the solids and the specific gravities of the solid material and the liquid material being fed to the inlet, the viscosity of the slurry material, and the pressure drop across the cyclone. Nevertheless, a high maintenance item of any cyclone is usually the apex. Typical prior art cyclone apexes include a cylindrical and/or conical body section with a liner which can be composed of loose ceramic, neoprene, urethane, or rubber, depending upon the abrasion and corrosion resistant properties needed for the material passing through the apex. The primary function of the apex is to discharge the coarse material at as high a density as possible without plugging the apex. Since the apex passes the coarser, sharp particles of the cyclone feed material, constant wear and high maintenance of the apex is a problem that has persisted historically. In most instances, the lower cone section, apexes, and anti-splash skirt extensions are all assemblies with "bolt on" flange connections. Due to the high liquid environment (usually water), rusting of the bolts interconnecting the flanges of the different removable sections typically occurs. Usually, removal of an apex is a two man operation, one worker using wrenches to remove the bolts, the other worker holding the apex and/or skirt in place. If excessive rusting has occurred, it may be necessary to call a welder, who cuts or "burns" the bolts off. For a large state-of-the-art cyclone which may have a diameter as large as two feet or more, the services of two workers are required for approximately fifteen minutes to one half hour to change one worn out apex. Typically, the apex of a cyclone may need to be changed as often as every two or three months, depending on the operation and ore characteristics. Occasionally, steel grinding balls and oversize ore are circulated through pumps and into the cyclones, usually the result of damaged screens, and can cause plugging of the cyclone and/or damage to rigid, ceramic type apexes and lower cyclone liners.
Typically, the splash skirt portion, if required, is attached to the lower flange of an apex and wears at a different rate than other parts of the cyclone. Ordinarily then, in order to replace the skirt section, it must be unbolted from the bottom flange of the apex. Furthermore, even though the lower portion of the cone does not wear as fast as the apex and skirt, it still wears considerably more rapidly than the upper portions of the cone. As a result, the lower cone sections also must be periodically replaced. The total amount of work and man-hours that are required for changing the lower cone sections, apex sections and skirt sections of conventional cyclones is high, increasing the cost of cyclone operations. It would be very desirable to allow cyclone apexes to be quickly replaced and in certain instances without turning off a particular cyclone. The state of the art is indicated in U.S. Pat. Nos. 3,902,601; 4,233,160; 3,984,308; 3,724,674; 2,897,972; 2,816,658; and 2,665,809. U.S. Pat. No. 3,902,601 discloses an apex insert which is seated in the lower portion of the cone. The cone is composed of urethane. The upper portion of it rests in and is surrounded by a steel upper cone sleeve and is a bolted connection. The apex insert may be replaced while the cyclone is in operation by removing a detachable ring attached to the bottom of the cone. The need for the replaceable cones and especially for easily replaceable apexes is recognized in U.S. Pat. No. 3,902,601, but the arrangement shown does not avoid the severe corrosion of bolts that must be loosened, nor does it avoid as much labor and inconvenience as is desirable. Although various ways of attaching apexes and lower cone sections and skirt sections to cyclones have been used in the prior art, the high amount of labor that is required for replacement of these portions of a cyclone has not been solved.
Accordingly, it is the primary object of the invention to provide an apparatus and method for achieving a quick release connection of an apex to a cone of a cyclone to allow rapid replacement or unplugging of the apex by a single worker.
It is another object of the invention to provide a low cost apex which can be discarded after use.
It is another object of the invention to eliminate metal housings and reduce the total number of components of a cyclone.
It is another object of the invention to provide a means for effectively replacing an apex of a cyclone without stopping the entire cyclone operation and without requiring the efforts of more than a single worker in the replacement operation.
It is another object of the invention to provide means for enabling an operator or worker to quickly and easily recognize when the apex of a cyclone needs to be replaced.
It is another object of the invention to provide a low cost apex assembly which both overcomes the difficulties associated with replacement of prior apex apparatus and also allows periodic adjustment of the diameter of the apex to compensate for ongoing abrasion thereof.
It is another object of the invention to quickly change the apex diameter for sudden changes in ore and grinding characteristics to effect better control of the entire grinding/classification circuits.